In a new report issued today, the Mercury Policy Project says children should never eat albacore tuna. It advises parents to limit light tuna to one serving per month for kids under 55 pounds, and to two monthly servings for bigger children.

“Today we unfortunately have to bring consumers a warning about tuna. Despite its popularity, it should be a rare meal for children,” Sarah Klein of the Center for Science in the Public Interest, one of the consumer groups in the coalition, said at a news teleconference.

The report includes tests of 59 samples of tuna from 11 states. The researchers purchased the tuna in the large 4-pound cans or foil packages from schools or from companies that supply schools.

The tests showed that mercury concentrations varied widely from can to can. Even separate samples from the same can carried very different amounts of mercury. The study found somewhat lower mercury levels in light tuna than in FDA tests, but higher levels in albacore tuna than the FDA reports.

Despite the study’s recommendations, the FDA stands by its own conclusions.

“FDA and EPA recommend that women of childbearing age and children consume no more than 12 ounces a week of canned light tuna and only 6 ounces per week of canned albacore tuna, which is higher in mercury. The average can of tuna holds 6 ounces of fish,” the FDA says in a statement.

Benefits vs. Harm

The report focuses only on the harms of tuna and not on its nutritional benefits, says Jennifer McGuire, RD, a dietitian at the Tuna Council of the National Fisheries Institute, a trade group that represents three major canned tuna producers.

“The report has no mention of omega-3 fatty acids, no mention of lean protein, and no mention of selenium, which has a positive interactive effect with mercury,” McGuire says. “They just pulled out the trace amounts of mercury in isolation and tried to make a fuss about it. There is really nothing new here to be concerned about.”

Edward Groth, PhD, the author of the coalition report, admits that most research on the effects of mercury has focused on pregnant women and early child development. He points to a 2009 study in Spain, which found that children with the highest mercury exposure had delayed mental development.

Groth’s report also mentions a 2009 study by pediatric neurologist Gary Myers, MD, that looked at the effects of extreme seafood-eating by children in the Seychelles islands. The study did find a link between eating fish, mercury levels, and mental development. But it concluded that the data “do not provide clear evidence” that the 9-year-old kids’ development was harmed by their mercury exposure.

Groth notes that a third of U.S. children’s mercury exposure comes from canned tuna.

“Don’t scare people away from giving kids tuna,” he said at the news conference. “It is not a question of tuna or no tuna, it is how much tuna. There are a lot of benefits from tuna, and the benefit is great when the intake is once or twice a month.”